That for the first time ever, under half the population in Ceredigion and Carmarthenshire now speak Welsh, that Welsh is the majority language in Gwynedd and Anglesey, nowhere else and that there too, the figures show a sharp drop in the numbers of Welsh speakers.

Ten years ago, the losses in the heartlands of the West were offset by big gains in the South East. Not this time. There are tiny increases in Cardiff and Monmouthshire - the sort that just about register a 0.1% uplift in percentage points - but those are swept aside by the losses in those areas where when you start speaking Welsh, you know that most people around you probably do too.

We may also remember that the biggest increase in the number of Welsh speakers is in the 3 - 5 year old category. The Welsh government "takes some comfort" from the extra 4.5% who ticked that box. Cue the questions of old about very young children and their parents who fill the census: the children go to a Welsh medium school, but do they 'speak Welsh?' Aren't Mum and Dad - if not "over reporting" - perhaps living in hope?

Others will argue that speaking Welsh is, in this context at least, as ill-defined a practice as being a Christian. Take one colleague who said that as a Welsh learner, or as she puts it, "a fluent eavesdropper" she found the Welsh-related questions "deeply unsatisfactory". Should she have put that she speaks, reads and writes Welsh when the answer is "to a degree ... To write yes to all those would make me seem, according to the census, just like you." She will have dealt with her dilemma in one way. Others will have come to a different conclusion and ticked a different box.

The Office for National Statistics don't really do "to a degree". This morning they politely explained that they can't really do "why" and "how come" either. They do facts. Ask them why the numbers of Welsh speakers is down here, there, pretty much everywhere and they'll tell you it's a combination of things - over-reporting in 2001, parents not speaking it to their children, older Welsh speakers dying, fewer children being born, bright, young Welsh speakers leaving the heartlands to come to Cardiff, leaving Wales and disappearing from the figures altogether. They'd point out too that though lower than 2001, the number of Welsh speakers is still higher in 2011 than it was in 1991.

Here's another, big factor to add to the mix - the facts around inward migration. Just over a quarter of the population of Wales was born elsewhere. In fact take a look at the figures from other European countries and you'll find only one where an even higher proportion of the population was born outside its borders - Luxembourg. Most by far of those who've moved to Wales have come from England. That inevitably goes some way to explain how the language is being diluted in areas where Welsh has been dominant for centuries.

As to identity - far greater experts than I am will look at the question, at the tick boxes and the figures and wonder what really we can glean from them.

Two things to finish: Carwyn Jones' children may not thank him but you suspect Mr Jones the Dad will have reached parts of the debate Mr Jones the First Minister could not have by revealing his own children speak Welsh in school - and to him - but never socially, outside school or to their friends. When he talks about "cracking that challenge" it's clear he's speaking from experience.

And one more set of figures: back in 2003 the Welsh government set a target of increasing the number of Welsh speakers by 5% by 2011. It's a target that seems entirely unrealistic now, in particular when you consider the irresistible force of demographics in all of this. They quietly scrapped it last year. Today it's become clear just how far it was out of their reach, long, long before they dropped it.